RESUMO
The bounded electrophoretic motion of a cylindrical particle in a circular cylindrical microchannel is explored for two cases: (1) the particle is located on the centerline of a channel (concentrically), with a symmetric wall boundary condition since gap width is constant throughout; and (2) the particle is at an eccentric location in the channel, with an asymmetric boundary condition set by the walls. The objective is to determine the effect of different boundary conditions, geometries, and physical properties on the velocity and orientation of the cylinder with respect to the boundary. A theoretical model for the motion of the cylinder is presented and the problem is solved numerically. The steady-state simulations show that the velocity of the cylinder is reduced at small gap widths for the concentric case, but the velocity is increased at small gap widths for the eccentric case. When the cylinder is angled with respect to the horizontal in the symmetric case or is near the boundary in the asymmetric case, vertical and rotational components of velocity are predicted. In such cases, transient simulations are appropriate for most accurately representing particle motion. Two such simulations are included herein and show both horizontal and vertical translation plus rotation of the particle as a function of time.
Assuntos
Modelos Químicos , EletroforeseRESUMO
A total of 280 cases of acute hepatitis B arising between 1979 and 1985 were retrospectively reviewed. Following an increase in the number of cases in 1983 and 1984, the incidence declined sharply in 1985. The main risk for infection was intravenous drug misuse (51.1%). Only one patient died from fulminant hepatitis. After leaving hospital, 110 patients were kept under surveillance. None suffered from chronic liver disease and none became a carrier of hepatitis B virus.
Assuntos
Hepatite B/epidemiologia , Doença Aguda , Adolescente , Fatores Etários , Idoso , Alanina Transaminase/sangue , Portador Sadio/epidemiologia , Criança , Pré-Escolar , Feminino , Hepatite B/etiologia , Vírus da Hepatite B/imunologia , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Fatores de Risco , Fatores Sexuais , Transtornos Relacionados ao Uso de Substâncias/complicaçõesRESUMO
Pulsed field gel electrophoresis (pfge) was used to compare 59 strains of Moraxella catarrhalis to evaluate pfge for the epidemiological typing of this organism. pfge-generated patterns were compared with those obtained by small fragment restriction enzyme analysis (rea) and species-specific probe hybridization. The strains used in the study were isolated from various geographic locations and included proven epidemiologically related strains. pfge yielded more unique patterns than dna-dna hybridization - 30 versus 18, respectively - but fewer than rea, which generated 45 unique patterns. Strains that demonstrated the same rea pattern or dna-dna hybridization pattern did not always demonstrate the same pfge pattern. For example, in 23 epidemiologically unrelated strains that shared six rea patterns, pfge differentiated the isolates into 12 patterns. Conversely, strains that demonstrated the same pfge pattern did not always demonstrate the same rea pattern or hybridization pattern. For example, in 42 strains that shared 13 pfge patterns, rea differentiated the isolates into 31 patterns and dna-dna hybridization differentiated them into 16 patterns. However, compared with rea, pfge yielded less complex patterns that were more easily comparable, and compared with dna-dna hybridization, pfge was technically easier.
RESUMO
AIM: To review the efficacy and tolerability of pegylated interferon-α and ribavirin for treatment of chronic hepatitis C (CHC) in children in the UK. METHODS: Retrospective review of children treated for CHC in 3 UK paediatric specialist liver centres between 2005 and 2010. Data on viral response to treatment, demographic and clinical details were collected. Treatment outcome was assessed by the absence of detectable viral RNA in blood 24â weeks after treatment-sustained viral response (SVR). RESULTS: 75 children were included; 34 genotype 1; 39 genotypes 2 and 3; 2 genotype 4. Overall SVR was achieved in 54/71 (76%); 65% genotype 1; 89% genotypes 2 and 3; 100% genotype 4. Early response at 12â weeks was achieved in 53 and sustained in 47 (89%). Data on rapid response after 4â weeks of treatment were available in 25; 17/25 (68%) responded and 16 of these (94%) achieved SVR. IL28 T/T genotype was associated with higher SVR. There were no significant changes in weight and height z scores from baseline compared with 24â weeks post-treatment follow-up. No child discontinued treatment due to side effects, although 43 required dose modification. Treatment affected quality of life (QoL) in the initial 12â weeks of treatment, which improved by the end of treatment. CONCLUSIONS: Children respond well to therapy for CHC. Treatment was tolerated with minimal impact on QoL and no significant effect on growth. Knowledge of viral and IL28 genotypes and early viral response is useful to plan treatment in children and provide appropriate counselling.
Assuntos
Antivirais/uso terapêutico , Hepatite C Crônica/tratamento farmacológico , Interferon-alfa/uso terapêutico , Polietilenoglicóis/uso terapêutico , Ribavirina/uso terapêutico , Adolescente , Criança , Pré-Escolar , Quimioterapia Combinada , Feminino , Genótipo , Hepatite C/genética , Hepatite C Crônica/genética , Humanos , Masculino , Polimorfismo de Nucleotídeo Único , Qualidade de Vida , RNA Viral/genética , Proteínas Recombinantes/uso terapêutico , Estudos Retrospectivos , Resultado do Tratamento , Reino UnidoRESUMO
HPS is defined as arterial hypoxemia because of pulmonary vasodilation as a result of cirrhotic or non-cirrhotic portal hypertension. This report describes a teenager with HPS because of primary sclerosing cholangitis/autoimmune hepatitis overlap syndrome requiring OLT. HPS resolved completely within three months of OLT, but recurred again at 12 months post-OLT following liver dysfunction secondary to a biliary stricture. She underwent a second OLT successfully and remains well two yr and three months post-second OLT. Recurrent HPS after OLT may occur because of graft dysfunction and as this novel case illustrates, retransplantation may lead to a successful outcome.
Assuntos
Síndrome Hepatopulmonar/cirurgia , Transplante de Fígado/métodos , Adolescente , Angiografia , Colangiopancreatografia Retrógrada Endoscópica , Feminino , Seguimentos , Síndrome Hepatopulmonar/diagnóstico , Humanos , Recidiva , Reoperação , Índice de Gravidade de Doença , Tomografia Computadorizada por Raios XRESUMO
Hepatitis C virus (HCV) infection in children is becoming an increasing challenge to health professionals. As our understanding of the disease evolves, so must our diagnostic and management strategies. In the 1990s, when HCV testing became available, children identified with HCV infection in the UK were mostly those who had required blood products, particularly those with haematological disorders. Acquiring knowledge of the natural history of HCV infection was confounded by the co-morbidity of iron overload, viral co-infection, and chemotherapy.
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Hepatite C/diagnóstico , Antivirais/uso terapêutico , Hepatite C/tratamento farmacológico , Hepatite C/transmissão , Humanos , Recém-Nascido , Transmissão Vertical de Doenças InfecciosasRESUMO
This report describes a teenager who developed aplastic anemia (AA) because of non-A-E acute liver failure (ALF) requiring orthotopic liver transplantation (OLT). His AA did not recover spontaneously and he required treatment with ATG 9 months post-OLT. Bone marrow recovery occurred 4 months after immunotherapy and coincided with further intensification of immunusuppression required to treat early chronic rejection of the liver graft. Three years post-OLT he remains well with good bone marrow and liver function. Intensification of immunosuppression can lead to successful resolution of AA associated with non-A-E ALF.
Assuntos
Anemia Aplástica/etiologia , Anemia Aplástica/cirurgia , Falência Hepática Aguda/complicações , Falência Hepática Aguda/cirurgia , Transplante de Fígado , Adolescente , Soro Antilinfocitário/uso terapêutico , Humanos , Imunossupressores/uso terapêutico , Testes de Função Hepática , MasculinoRESUMO
OBJECTIVE: To investigate the use of (99m)Tc-HMPAO (hexamethyl propylene amine oxime) leucocyte scintigraphy as a non-invasive screening test for inflammatory bowel disease. PATIENTS: 10 children with suspected Crohn's disease, in whom routine investigation using barium contrast radiology, upper gastrointestinal endoscopy, colonoscopy, and mucosal biopsies had identified severe gastroduodenal and/or jejunal involvement. DESIGN: (99m)Tc-HMPAO leucocyte scintigraphic studies performed in each of these cases were assessed by a radiologist who was blinded to the disease distribution. RESULTS: In nine cases there was no scintigraphic evidence of inflammation in the proximal gastrointestinal tract. The 10th child had both gastroduodenal and jejunal involvement, but scintigraphy only revealed faint jejunal positivity. CONCLUSIONS: (99m)Tc-HMPAO leucocyte scintigraphy should not be depended upon as a screening test for Crohn's disease. False negative results are likely in cases with Crohn's disease confined to the proximal gastrointestinal tract.
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Doença de Crohn/diagnóstico por imagem , Gastrite/diagnóstico por imagem , Compostos Radiofarmacêuticos , Tecnécio Tc 99m Exametazima , Sulfato de Bário , Biópsia , Criança , Meios de Contraste , Doença de Crohn/patologia , Duodenite/diagnóstico por imagem , Endoscopia Gastrointestinal , Enterite/diagnóstico por imagem , Reações Falso-Negativas , Humanos , Valor Preditivo dos Testes , CintilografiaRESUMO
The Epstein-Barr virus is associated with a broad spectrum of lymphoproliferative diseases in liver allograft recipients. To investigate the effects of primary infection in children following liver transplantation and the possible role of Epstein-Barr virus in the pathogenesis of unexplained chronic hepatitis after transplantation, we used an in situ hybridization technique to detect small virus encoded nuclear RNAs in posttransplant specimens. For comparison, other posttransplant complications and diseases occurring in the nontransplanted liver were studied with the same method. We examined 114 specimens in the following categories: (a) children with primary Epstein-Barr virus infection after transplant (n = 25), (b) chronic hepatitis more than 12 mo after transplant (n = 14), (c) rejection (n = 15), (d) normal/near-normal histology more than 12 mo after transplant (n = 13) (e) end-stage acute liver disease (n = 9) and (f) end-stage cirrhosis (n = 38). Thirty-three of 114 specimens had labeling of occasional portal and parenchymal lymphoid cells. These were present in each of the six main diagnostic categories listed above: 2 of 25, pediatric; 6 of 14, chronic hepatitis; 4 of 15, rejection; 1 of 13, normal; 4 of 9, acute; and 16 of 38, cirrhosis. In none of the patients with Epstein-Barr virus-infected cells did lymphoproliferative disease subsequently develop. In conclusion, we have been unable to show an obvious association between Epstein-Barr virus infection and graft dysfunction after liver transplantation. Our results suggest that immunological response to primary infection in children after liver transplantation may be adequate.(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Hepatite Viral Humana/virologia , Infecções por Herpesviridae/virologia , Herpesvirus Humano 4/isolamento & purificação , Transplante de Fígado , Fígado/virologia , Complicações Pós-Operatórias/virologia , Infecções Tumorais por Vírus/virologia , Biópsia , Pré-Escolar , Doença Crônica , Feminino , Hepatite Viral Humana/patologia , Infecções por Herpesviridae/patologia , Herpesvirus Humano 4/genética , Humanos , Hibridização In Situ , Lactente , Fígado/patologia , Transplante de Fígado/patologia , Masculino , Complicações Pós-Operatórias/patologia , RNA Viral/análise , Infecções Tumorais por Vírus/patologiaRESUMO
OBJECTIVE: To determine whether cytomegalovirus (CMV) is associated with gingival overgrowth in paediatric liver graft recipients treated with cyclosporin. STUDY DESIGN: Thirty-four children, 25 of whom were under 5 years of age, who had undergone liver transplantation, were examined. An Index of Severity of Gingival Overgrowth was used to measure the prevalence and severity of the gingival overgrowth. The trough cyclosporin level was recorded and the CMV status of the patient matched to the dental findings. The association between the severity of gingival overgrowth and CMV infection was examined using the contingency coefficient. An anova was used to assess the association between the circulating trough cyclosporin concentration and the severity of gingival overgrowth. Pearson's Product Moment Correlation Coefficient was used to examine the association between the duration of exposure to cyclosporin and the severity of gingival overgrowth. RESULTS: There was a significant inverse association between the duration of exposure to cyclosporin and the severity of gingival overgrowth. There was no relationship between the trough cyclosporin concentration and the severity of gingival overgrowth. There was no association between CMV and gingival overgrowth. CONCLUSION: Gingival overgrowth was related to the duration of cyclosporin therapy but was neither more prevalent nor more severe in subjects who were CMV seropositive.
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Ciclosporina/efeitos adversos , Citomegalovirus/patogenicidade , Crescimento Excessivo da Gengiva/virologia , Imunossupressores/efeitos adversos , Transplante de Fígado , Análise de Variância , Criança , Pré-Escolar , Infecções por Citomegalovirus/sangue , Infecções por Citomegalovirus/complicações , Feminino , Crescimento Excessivo da Gengiva/induzido quimicamente , Crescimento Excessivo da Gengiva/patologia , Humanos , Lactente , Masculino , Índice Periodontal , Estatísticas não Paramétricas , ViremiaRESUMO
This report describes a 16-month-old girl with multi-system Langerhans cell histiocytosis (LCH), who developed end-stage liver disease despite intensive chemotherapy. She underwent a liver transplant at 28 months of age while receiving maintenance chemotherapy for bony lesions. In view of previous reports of a high incidence of acute cellular rejection and post-transplant lymphoproliferative disease (PTLD) in children transplanted for LCH, basiliximab was added to the post-transplant immunosuppression regime of tacrolimus and prednisolone. Sixteen months post-transplant, she has had no episodes of acute rejection or PTLD and her LCH has remained in remission. Current literature regarding liver transplantation (LTx) for LCH and the use of basiliximab in pediatric LTx is reviewed.
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Anticorpos Monoclonais/uso terapêutico , Histiocitose de Células de Langerhans/cirurgia , Imunossupressores/uso terapêutico , Transplante de Fígado , Proteínas Recombinantes de Fusão , Basiliximab , Feminino , Humanos , Lactente , Falência Hepática/etiologia , Falência Hepática/cirurgia , Prednisolona/uso terapêutico , Tacrolimo/uso terapêuticoRESUMO
BACKGROUND/AIMS: Chronic graft hepatitis occurs in 20-30% adults after liver transplantation but the prevalence and causes in children are not known. In adults, hepatitis C virus infection is prevalent prior to transplantation and recurrent infection is a frequent cause of graft dysfunction. The significance of the recently described hepatitis G virus infection remains unproven. The aim of this study was to examine the role of hepatitis C virus and hepatitis G virus infection in chronic graft hepatitis after paediatric liver transplantation. METHODS: The prevalence of graft hepatitis and the role of hepatitis C virus and hepatitis G virus infections in 80 children after liver transplantation have been studied, with a median follow up of 4.4 years (range 0.4 to 10.7), and the persistence of hepatitis G infection in the presence of immunosuppression has been determined. RESULTS: Chronic graft hepatitis was diagnosed in 19/80 (24%) children and was most frequently seen in children transplanted for cryptogenic cirrhosis (71%). There was no significant difference in the prevalence of chronic hepatitis in those transplanted before or after donor anti-HCV screening. Hepatitis C infection occurred in three children transplanted prior to donor screening but in only one was associated with chronic hepatitis. Hepatitis G infection was found in 22/79 (28%) transplant recipients but was not associated with graft hepatitis. In 17/21 children hepatitis G infection persisted for a median of 5.2 years after transplantation. CONCLUSION: Chronic hepatitis occurred in 24% of children after liver transplantation, a similar prevalence to that in adults. Cryptogenic liver disease predisposed to graft hepatitis, but neither hepatitis C nor hepatitis G infection was associated. Hepatitis G virus caused a frequent and usually persistent infection after transplantation.